Gasoline, the lifeblood of your lawn mower, doesn’t last forever. Understanding its shelf life and the factors that affect it is crucial for maintaining your mower’s performance and preventing costly repairs. Let’s dive into the science behind fuel degradation and learn how to keep your lawn mower running smoothly.
The Deterioration of Gasoline: A Chemical Breakdown
Gasoline is a complex mixture of hydrocarbons. Over time, these hydrocarbons undergo chemical changes, leading to the formation of gums, varnishes, and other deposits. This process, known as oxidation, is accelerated by exposure to air, heat, and sunlight.
Understanding Oxidation and its Effects
Oxidation occurs when gasoline reacts with oxygen in the air. This reaction creates unwanted byproducts that can clog fuel lines, carburetors, and other engine components. The result is poor engine performance, difficulty starting, and, in severe cases, engine damage.
The Role of Ethanol in Gasoline Degradation
Many gasoline blends contain ethanol, an alcohol added to increase octane and reduce emissions. While ethanol has its benefits, it also has a significant drawback: it attracts water. This water absorption leads to phase separation, where the ethanol and water separate from the gasoline, forming a corrosive mixture that can damage fuel systems.
The Lifespan of Gasoline in a Lawn Mower
The lifespan of gasoline in a lawn mower depends on several factors, including the type of gasoline, storage conditions, and the presence of ethanol.
Regular Gasoline: A Shorter Shelf Life
Regular gasoline, without fuel stabilizers, typically lasts for 3 to 6 months. After this period, it starts to degrade, losing its octane rating and forming harmful deposits. The exact timeframe depends on the temperature and exposure to air.
Ethanol-Blended Gasoline: An Even Shorter Window
Gasoline containing ethanol (typically E10, which is 10% ethanol) has an even shorter shelf life, usually around 1 to 3 months. The ethanol attracts moisture, leading to phase separation and corrosion of fuel system components. This is especially problematic in humid environments.
Premium Gasoline: Not Always the Answer
While premium gasoline may have a higher octane rating, it doesn’t necessarily mean it lasts longer. The degradation process is similar for both regular and premium gasoline, especially if they contain ethanol. Focus on proper storage and fuel stabilizers, rather than solely relying on premium fuel for extended storage.
Factors Affecting Gasoline Shelf Life
Several environmental and storage-related factors play a significant role in how quickly gasoline degrades.
Temperature: The Heat is On
High temperatures accelerate the oxidation process. Storing your lawn mower in a hot shed or garage will significantly shorten the lifespan of the gasoline. Cooler temperatures help to slow down the degradation process.
Exposure to Air: A Breeding Ground for Degradation
Gasoline needs to be stored in an airtight container to minimize exposure to oxygen. A loosely sealed gas tank allows air to enter, promoting oxidation and evaporation, leading to a stale and unusable fuel.
Sunlight: An Unseen Enemy
Sunlight can also contribute to gasoline degradation. UV rays can break down the hydrocarbons in the fuel, leading to the formation of gums and varnishes. Store your lawn mower and fuel containers in a dark, cool place to protect them from sunlight.
The Container Matters
The type of container used to store gasoline also impacts its lifespan. Always use a certified gasoline container designed to prevent leaks and minimize evaporation. Avoid using old or damaged containers, as they may not provide adequate protection.
The Consequences of Using Old Gasoline
Using old gasoline in your lawn mower can lead to a range of problems, from minor inconveniences to major engine damage.
Difficulty Starting: A Common Symptom
One of the first signs of using old gasoline is difficulty starting the engine. The degraded fuel may not ignite properly, requiring multiple attempts to start the mower.
Poor Engine Performance: A Loss of Power
Old gasoline can cause poor engine performance, including reduced power, rough idling, and stalling. The gums and varnishes formed by the degraded fuel can clog fuel lines and carburetors, restricting fuel flow.
Clogged Carburetor: A Costly Repair
A clogged carburetor is a common problem caused by using old gasoline. The deposits from the degraded fuel can block the small passages in the carburetor, preventing it from delivering the correct air-fuel mixture to the engine. Cleaning or replacing a carburetor can be a costly repair.
Engine Damage: The Worst-Case Scenario
In severe cases, using old gasoline can lead to engine damage. Phase separation in ethanol-blended gasoline can cause corrosion of fuel system components, leading to leaks and engine failure.
Preventative Measures: Keeping Your Fuel Fresh
Fortunately, there are several steps you can take to prevent gasoline degradation and keep your lawn mower running smoothly.
Using Fuel Stabilizers: A Protective Shield
Fuel stabilizers are chemical additives that help to prevent gasoline degradation. They work by inhibiting oxidation, preventing the formation of gums and varnishes, and stabilizing the fuel for extended storage.
How Fuel Stabilizers Work
Fuel stabilizers contain antioxidants and metal deactivators that protect the fuel from oxidation and corrosion. They also help to prevent phase separation in ethanol-blended gasoline. Add fuel stabilizer to your gasoline every time you fill up your gas can, following the manufacturer’s instructions.
Choosing the Right Fuel Stabilizer
There are many different fuel stabilizers available on the market. Look for a stabilizer specifically designed for small engines and that is compatible with ethanol-blended gasoline. A good fuel stabilizer can extend the lifespan of gasoline up to 24 months.
Proper Storage: The Key to Longevity
Proper storage is essential for maintaining the quality of gasoline. Store your lawn mower and fuel containers in a cool, dry, and dark place, away from direct sunlight and heat sources.
Emptying the Fuel Tank: A Seasonal Ritual
If you plan to store your lawn mower for an extended period, such as over the winter, it’s best to empty the fuel tank completely. This prevents the gasoline from degrading and causing problems when you start the mower again in the spring.
Running the Engine Dry
After emptying the fuel tank, start the engine and let it run until it stalls. This ensures that all the gasoline is removed from the carburetor and fuel lines.
Treating the Fuel System: Extra Protection
Consider using a fuel system cleaner to remove any deposits that may have formed in the carburetor and fuel lines. This will help to ensure that the engine starts easily and runs smoothly.
Regular Maintenance: A Proactive Approach
Regular maintenance is essential for keeping your lawn mower in good condition. This includes changing the oil, cleaning the air filter, and inspecting the spark plug. A well-maintained lawn mower will run more efficiently and be less likely to experience problems caused by old gasoline.
The Importance of a Clean Air Filter
A dirty air filter can restrict airflow to the engine, causing it to run rich and inefficiently. This can lead to incomplete combustion and the formation of carbon deposits in the engine. Clean or replace the air filter regularly to ensure optimal engine performance.
Checking the Spark Plug
A faulty spark plug can also cause starting problems and poor engine performance. Inspect the spark plug regularly and replace it if it is worn or fouled.
Reviving Old Gasoline: Is it Possible?
While prevention is always the best approach, you may find yourself with a gas can full of old gasoline. Can it be salvaged?
The Risks of Using Revived Gasoline
While it might be tempting to try and revive old gasoline, it’s important to understand the risks. Degraded gasoline can still cause problems, even after adding fuel stabilizer. The gums and varnishes that have already formed may not dissolve completely, and the fuel may still have a lower octane rating.
When Revival Might Be an Option
If the gasoline is only slightly degraded (less than 6 months old and stored properly), you may be able to revive it by adding a double dose of fuel stabilizer. However, it’s best to use this gasoline in a less critical application, such as a car engine, where the effects of using slightly degraded fuel are less noticeable.
The Safe and Responsible Disposal of Old Gasoline
The best and safest way to deal with severely degraded gasoline is to dispose of it properly. Contact your local waste management facility or hazardous waste collection center to find out how to dispose of gasoline safely and legally. Never pour gasoline down the drain or into the ground, as this can contaminate water sources.
Alternative Fuels: Exploring Your Options
While gasoline is the most common fuel for lawn mowers, there are alternative fuels available, each with its own set of advantages and disadvantages.
Propane: A Clean-Burning Option
Propane is a clean-burning fuel that produces fewer emissions than gasoline. Propane-powered lawn mowers are becoming increasingly popular, but they require a special conversion kit and may not be as readily available as gasoline-powered models.
Electric Lawn Mowers: A Cordless Revolution
Electric lawn mowers are another alternative to gasoline-powered models. They are quiet, easy to maintain, and produce no emissions. Electric lawn mowers can be corded or cordless, with cordless models offering greater freedom of movement. However, electric lawn mowers may not be as powerful as gasoline-powered models, and their runtime is limited by the battery capacity.
Conclusion: Maintaining a Healthy Fuel System
Understanding the lifespan of gasoline in your lawn mower and taking preventative measures is essential for maintaining a healthy fuel system and ensuring optimal engine performance. By using fuel stabilizers, storing gasoline properly, and performing regular maintenance, you can avoid the problems associated with old gasoline and keep your lawn mower running smoothly for years to come. Always prioritize safety and responsible disposal practices when handling gasoline. Remember that a proactive approach to fuel management will save you time, money, and headaches in the long run.
How long can gasoline sit in a lawn mower before it starts to go bad?
Generally, gasoline can start to degrade in as little as 30 days, but most sources suggest that unleaded gasoline begins to noticeably degrade within 3 to 6 months. Factors like temperature, humidity, and the presence of ethanol can accelerate this process. Ethanol-blended fuels are particularly prone to absorbing water, which can further degrade the fuel and cause engine problems.
For optimal engine performance, it’s best to use fresh gasoline in your lawn mower. If your mower will be stored for more than a month, it’s advisable to either drain the fuel tank and carburetor or add a fuel stabilizer to help prevent the fuel from going bad. This will help prevent issues like hard starting, rough running, and carburetor clogging.
What are the signs of bad gas in my lawn mower?
One of the most common signs of bad gas is difficulty starting the engine. You might find that the engine cranks for a long time without firing, or it may start briefly and then stall. A noticeable change in the fuel’s smell can also be a strong indicator of degradation – old gasoline often has a sour or varnish-like odor compared to the fresh, sweet scent of good fuel.
Beyond starting issues, your lawn mower may run roughly or irregularly with bad gas. This can manifest as sputtering, hesitation, or a general lack of power, especially under load. You might also notice excessive smoke coming from the exhaust. In more severe cases, bad gas can lead to carburetor clogs and require professional cleaning or repair.
How does ethanol in gasoline affect the shelf life of fuel used in lawn mowers?
Ethanol is an alcohol additive found in many gasoline blends, primarily to boost octane levels. Unfortunately, ethanol attracts and absorbs water from the air. This water absorption can lead to phase separation, where the ethanol and water separate from the gasoline, forming a layer at the bottom of the fuel tank. This phase separation renders the remaining gasoline unusable and can corrode fuel system components.
Due to its affinity for water, ethanol-blended gasoline has a shorter shelf life compared to pure gasoline. The water absorbed by the ethanol can cause rust and corrosion in the fuel tank and carburetor, leading to performance issues and potential damage. When storing your lawn mower for extended periods, it is always preferable to use ethanol-free gasoline or treat ethanol-blended fuel with a fuel stabilizer.
What is a fuel stabilizer, and how does it help extend the life of gasoline in a lawn mower?
A fuel stabilizer is a chemical additive designed to prevent the degradation of gasoline during storage. It works by inhibiting oxidation, which is the primary process that causes gasoline to break down. Fuel stabilizers also contain detergents that help keep the fuel system clean and prevent the formation of gum and varnish, which can clog carburetor jets and fuel lines.
By using a fuel stabilizer, you can significantly extend the shelf life of gasoline in your lawn mower, often up to 12-24 months. The stabilizer helps to keep the fuel fresh, ensuring that your engine starts easily and runs smoothly after periods of storage. It’s essential to add the stabilizer to the fuel according to the manufacturer’s instructions, typically before storing the mower.
Is it better to drain the gas tank of my lawn mower or use a fuel stabilizer when storing it?
Both draining the gas tank and using a fuel stabilizer are effective methods for preparing your lawn mower for storage. Draining the tank eliminates the risk of fuel degradation altogether, as there’s no fuel left to go bad. This is particularly beneficial if you anticipate storing the mower for a very long time, like over the winter months. Make sure to run the engine until it stalls to remove any remaining fuel from the carburetor.
However, using a fuel stabilizer is often more convenient. It prevents the need to handle potentially hazardous gasoline and ensures that the fuel system remains lubricated. The stabilizer protects the fuel from breaking down and keeps the fuel system clean. For shorter storage periods (e.g., a few months), a fuel stabilizer is typically the preferred method, provided that the fuel is relatively fresh to begin with.
Can I reuse old gasoline from my lawn mower if it doesn’t smell too bad?
While it might seem tempting to reuse old gasoline, even if it doesn’t have a strong odor, it’s generally not recommended. Gasoline can degrade even without a noticeable change in smell. The lighter, more volatile components of the fuel evaporate over time, reducing its octane rating and making it harder to ignite. These changes can lead to starting problems and decreased engine performance.
Using degraded gasoline can also cause engine damage in the long run. The degraded fuel can leave deposits in the fuel system, clogging carburetor jets and fuel lines. It is always best to discard old gasoline properly and use fresh fuel to ensure optimal engine performance and longevity of your lawn mower.
How should I properly dispose of old gasoline from my lawn mower?
Disposing of old gasoline properly is essential for environmental protection. Never pour gasoline down drains, into the sewer, or onto the ground, as this can contaminate water sources and harm wildlife. Many communities have hazardous waste collection programs where you can safely dispose of gasoline and other chemicals.
Contact your local waste management facility or check your city or county’s website for information on hazardous waste disposal. Some auto repair shops or recycling centers may also accept old gasoline for recycling or proper disposal. Ensure you store the old gasoline in a sealed, approved container before transporting it to a disposal facility.